Electric system



addition. to a system Patented Jan. 2%, i926.

*UNITED s'rArss GEORGE T. BB-UUN, OF PITTSBURGH. TENNSYLVANIA.

ELECTRC SYSTEM.

4@riginal application filed January 147, 1922, Serial No. 529,916. Divided and this applic-ation filed Feb-faery .To r//Z lacl/om it may Concern.'

lie it known that l. (trionfale 'l`. Buona'. a citizen ot' the. United States. and resident ot' Pittsburgh. in the. county of iiltcghcny and State ot' Pennsylvania, have invented a rcw and usct'ul Improvement in ltllectric. iiys tenis: and i do hcrchy declare the. following to he a full, clear, and exact description thereof.

My invention relates to electric distribution and power systems which include satety switches or disconnecting switches.

'lhe .object of my invention is to protect safety switches and disconnecting switches trom thcdamage which frequently results when the switch opened while heavy cui rent is o n thcline and which also frclpiently causes injury or loss of lite to the person who opens the switch.

More specifically, my object is to protect heavy-duty switches, herein called for convenience main switches", hy preventing the. main switch from being opened or closed while heavy current is tiowing through it.

My invention consists, in general, in the including a main Switch, whether a safety switch or a clisconnecting switch` of an auxiliary contact` device mechanically attached tothe main switch, or to a movable element associated with thel main switch, and arranged to open, close or shunt a control circuit which includessome means, such as a motor starter, a circuit breaker, or other circuit-interrupting device', which will interrupt or reduce the current in the main circuit before the main switch is opened, therehy eliminating the possibility of dangerous ares at the main switch. The auxili-ary switch similarly proteets the, main switch when the switch is being closed, by preventing the flow of heavy current in the main circuit until the main switch is` completely cl'sed.

in industrial motor circuits it is now customary to connect a safety type switch in the motor circuit ahead ot" the starter, and disconnecting switches are generally used for higher voltages and higher current to disconnect apparatus from the line. lt often happens that switcher off this sort are opened by 'niistal e.-\\'lie.1. carrying heavy current, with resulting damage and casuah ties. In such eases when, for example, a motor is stopped byA the safety switch instead of by the starter, a condition results Serial No. 619,012.

which may partly or wholly destroy the .switch with conselptcut inliury or loss of lite to thc operator. especially when a switch ot large capacity is thus opened. 'the open: i ig ot' ,such switches under load is pronihit cd hy electrical code aulhoritics,h11t it ottcn happens that' such .switchesA are opened under load` either hy mistake or in emergencies.

s applied to the control of motor circuits, my invention aims to avoid the dan gers mentioned ahove hy equipping the .safety switch with an auxiliar)Y switch through which passes the controlling eurrcnt ot' the starter. rthe satcty switch and the auxiliary switch arc so connected mcchauically that the auxiliary switch opened lct'ore thc niain switch, so that the starter will open and disconnect the motor trom the line het'ore the main switch opens., and will also make it impossible to start the motor hetore the sat'cty switch is positively closed and is making vfull contact. thereby prerenting the switch trom being unduly heated.

',lhe. same principle. may he cuiploycd in various other connections. Thus the main switch on a `starter panel may be provided with an auxilialy switch or with auxiliary contacts so connected as to keep the main line open until the :nain switch is fatty closed, and to open the main contacter or circuit hrealter before thc switca is opened.

Also7 disconnecting switches` safety switches or other heavy-dutyswitches may he provided with auxiliary contacts so con uected as to operate a circuit breaker het" the discimnccting or .safety switch is open. ly this means. damage is prev-t in case anyone should attempt to opery disconnecting switch under load. which frequently happens, and which is likely to injure the person operating the switch and to interrupt the continuity ot service. through damage to the surrounding appa*- ratus, or by setting up surges in the line.

For a tui-ther understanding ot my invention, reference may now he had to the accompanying drawing. in which l a. side elevational yiew ot one of the many l'orius in which my device may he. constructed: Fig. 2 is a side elevational View of another torin of my device; Fig. is a fragmentary sectional view taken onthe line S-B=`Fig. Q; Fig. 4 is a diagram of a typical motor circuit showing the application titl titi` fingers 15.

of my invention thereto; and lig. 5 is a diav gram showing another typi almotor circuit equipped with my invention.

Referring' first to Fig. l et the drawing, the system therein shown comprises a threephase motor 2 provided with an automatic starter 3 and with a safety switch 4C through which the motor is connected to line conductors The starter is controlled by means ot a stop-and-start pushsbutton switch indicated diagrammatically at t3. The control circuit which is operatedby the puslrbutton switch 6 includes a conductor 7 in which is inserted an auxiliary contact device 8 which is connected mechanically to a movable part ot the safety switch' #ls in any suitable manner, examples of such connections being' shown in 1 to 3 ot the drawing.

Fig. 5 is a typical diagram of a motor circuit including a hand compensator. rthe niotor 2, as in Fig.. 3, is provided with a satety switch Ll, and 4with an auxiliary con-k tact device 8 n'iechanically'connected to the I switch Ll and arranged to operate the control circuit which includes the conductors and 10 and a low voltage release 11. The other connections shown in Fig. 5 are ot ordinary standard construction and are theretore not described in detail.

The mechanical design and operating` connections for the auxiliary contact device may he made in many diilerent ways, the only requirement being that the auxiliary contact device shall open the control circuit be'tore the main switch opens the main circuit, and that the auxiliarycontact device shall close the control circuit atter the main switch has closed the main circuit. By way of showing examples of such connections .vithout, however, limiting my invention to the constructions here shown, I have illustrated on the drawing` two simple methods of connectingthe auxiliary contact device to the main switch.

In Fic. 1- the main switch consists of one or more blades 1:2 pivoted at 13 to the usual post 14 and arranged to fit between. contact The main circuit conductors are shown at 16. An auXiliary'blade 17 is carried by a block 18 of insulating material secured to the blade 12 or to any other movable portion et lthe switch. The auxiliary blade 1( 'engages stationary contact lingers 19 when the switch is'fully closed, and the contact fingers 19 are connected to control circuit conductors 20.

lThe blade 12 is shown in tull linev en Fig. 1in the position in which both the main switch and the auxiliary switch are fully closed. Thisligure also shows in dotted lines the position of the blades in which the @main switch blade 12 is still in contact with the lingers 15, while the auxiliaryblade 17 has broken lingers 19.

Contact with the auxiliary it will be evident that when the Lacasse switch ot Figi 1 is opened thc auxiliary rou trol circuit is broken before the main circuil is broken, and that when the switch is closed the main circuit is closed before the control circuit is dosed.

Figs. 2 and 3 show one method in which my invention may be carried out by the use ot' an auxiliary switch olx the push-button type. ln these Iigurcs the blade 12 t' the main switch carries a 'foi-lied member fil midway between its ends. The member 2l is arranged directly above the push button et au ordinary ymsh-button switch ot the open type, the contact member 33 ot which is adapted to close the control circuit El. A spring tends to hold the switch in its open position. When the blade 12 is lowered to close the main circuit the member 21. forces down the push button and closes the control circuit 24 and does so after the main switc i. blade 12 has engaged the lingers 1:3 to close the main circuit.

The main switch may be et any usual or desired type and may be a single pole, double pole or triple pole switch, or with any number of poles. lt can be ot' the quick makeand-brealr type, air-break type, oil-switch type, con;1pensator-switch type, or yany other type with solid or brush contact. 'lhis switch may be a single throw' or double throw switch, it may be tused or unt'used, and may be arranged in all respects accord ing to standard practice without any changes or additions except the addition ot the auxiliary contact device.

The auxiliary control circuit contact di. vice may be mounted on, or attached to, the main switch blade by means ogt insulating' materialvas shown in Fig. 1, or may be op? erated directly'by the switch handle or by anyv moving part of the switch, or even bv the hookstick for disconnecting,- switches, and can be mounted ahead or behind the switch` blade or between the blades of the switch. The stationary contacts ot' the auxiliary device may be mounted on the switch base, .er at a distance, or for enclosed switches may be placed on the box. Like the Lil main switch it may be of any ordinary or desired type. lf tact device may be connected to operate a signal lamp or bell, so as to indicate' visibly or audibly the condition ofthe. main' circuit. hiy invention makes it unnecessary, as a rule, to construct safety switches with special arrangements for quick make-and-break action, as is new customary, since the safety switch breaks no heavy currentwhen connected according to my invention. YThe'cost ot such special quick-acting switches is thus 1 saved.

,. As stated above, the auxiliary centact'device may be mechanically connected not only to the main switch itself, but to any movin@ part associated with the switch. When desired, the auxiliary cenl minces cover oft/tire hon., thereby preventing the hon e from being opened becre the circuit through the switch is interrupted. This maires it 'pcssibie :to encicse the safety switch in en crdinery hos, without the necessity of comu ine-cherries? interlocking mechanism which is new used for preventing` the cover :from being opened While the setes ciosed.

e'contact deviee'cnn also he l so tiret a suhstentiel time intcrvsi may occur between the opening of the euriiiery contect and the opening of the inein switch.

It wili else he noted that the present sysieni provides for interrupting the inuin cir cuit by means of circuit breaker or mugnetic switch, without requiring any ext-re apparatus of this kind, The auxiliary contact device, when connected to the circuit hreulfer or magnet-ic switch ordineriiy found i in eiectric circuits off any considerable cc.-

'pocityg wiii cause such circuit interrupter to not hei'ore the mein switch is opened, end will inintein the circuit interrupter open until the mein tcii lis ciosed, The use cf expensive individu-ei circuit breakers for each motor or other appliance is thereby avoided, whiie providing equivaient protection.

it will thus be seen that iny invention may loe carried out in en almost unlimited mint seV .her ci? ways, :ind I therefore desire that ymy invention may be understood as not beingl iiinited to the particular constructions sind arrangements herein described.

This zipplicetion is e division of rny cosending application for Letters Patent filed iiennery 1'?, 1922, Serial No. 529,916.

i claim as my invention:

, An electric system comprising :L main circuit and n translating device, a manuallyand im. electrically-opernble switch between the circuit and thc device, a holding coil requiring energizution to hold the electricallyoperzible switch closed, and an auxiliary switch associated with the manually-operable switch for closing the holding coil circuit after the manually-operable switch is closed and. for opening the holding coil circuit before the :nununlly-opcrable switch is opened.

2. An electric system comprising a main circuit for energizing e translating device, e menuallywperahle switch :for said main circuit, an electrically-operable switch for connecting the translating device to the main circuit, and en auxiliary circuit controlled by the manually-operable switch and adapted when energized to permit the operation and closure of the electricaliy-operahle switch7 and when cle-energized, to preclude the electriceiiympernble switchl from latching in closed position.

in testimony whereo i the said GEORGE T. ERUUN, have hereunto set my hand.'

GEORGE T. BRUUN. 

